In recent years, in the field of display devices, there is a tendency to increase the length and/or the number of signal lines in accordance with an increase in size and high definition of a display device. There is also a tendency to increasingly thin the signal lines so as to increase an aperture ratio which directly affects the transmittance of a display panel.
Such tendencies have increased the possibility of causing a defect such as electric disconnection of a signal line in the display device.
Conventionally, in a case where a display device causes a defect such as electric disconnection of a signal line, the defect is repaired so that the display device is driven.
FIG. 25 illustrates, as an example of the above case, a liquid crystal display device which includes electric wires and repair circuits which are used to repair defects, such as electric disconnection of data signal lines, in a case where the defects occur so that the liquid crystal display device is driven.
As illustrated in FIG. 25, a liquid crystal display device 109 includes (i) a liquid crystal display panel 100 and (ii) a control substrate 108 that is connected to the liquid crystal display panel 100 via an FPC 107.
The liquid crystal display panel 100 has a display region R1 in which a plurality of pixels (not illustrated) are arranged in a matrix manner. The liquid crystal display panel 100 includes (i) a scan signal line driving circuit (gate driver) 101 for supplying scan signals to a plurality of scan signal lines (not illustrated) and (ii) a data signal line driving circuit (source driver) 102a and a data signal line driving circuit (source driver) 102b each for supplying data signals to a plurality of data signal lines S1, S2, . . . , and S′(2n). The scan signal line driving circuit 101 and the data signal line driving circuits 102a and 102b are provided around the display region R1.
In the display region R1, the plurality of scan signal lines and the plurality of data signal lines S1, S2, . . . , and S′(2n) intersect with each other (not illustrated). In the vicinity of intersections where the plurality of scan signal lines and the plurality of data signal lines S1, S2, . . . , and S′(2n) intersect with each other, there are provided respective switching elements (not illustrated), such as TFTs, which are electrically connected to pixel electrodes of the respective plurality of pixels.
As illustrated in FIG. 25, the data signal line driving circuit 102a includes (i) a source amplifier circuit 103a for supplying data signals to the data signal lines S1, S2, . . . , and S(2n) and (ii) a repair amplifier circuit 104a which is used to repair electric disconnection of the data signal lines S1, S2, . . . , and S(2n) in a case where the electric disconnection occurs so that the liquid crystal display device 109 is driven.
A preliminary wire 105a is provided in a region between the display region R1 and the data signal line driving circuit 102a so as to intersect end parts of the respective data signal lines S1, S2, . . . , and S(2n), which end parts are on a side of the data signal line driving circuit 102a. A preliminary wire 106a is provided so as to (i) extend to a region other than the display region R1 and (ii) intersect the other end parts of the respective data signal lines S1, S2, . . . , and S(2n).
The repair amplifier circuit 104a has (i) an input terminal to which the preliminary wire 105a is electrically connected and (ii) an output terminal to which the preliminary wire 106a is electrically connected.
Similar to the data signal line driving circuit 102a, the data signal line driving circuit 102b includes (i) a source amplifier circuit 103b for supplying data signals to the data signals S′1, S′2, . . . , and S′(2n) and (ii) a repair amplifier circuit 104b which is used to repair electric disconnection of the data signal lines S′1, S′2, . . . , and S′(2n) in a case where the electric disconnection occurs so that the liquid crystal display device 109 is driven.
A preliminary wire 105b is provided in a region between the display region R1 and the data signal line driving circuit 102b so as to intersect end parts of the respective data signal lines S′1, S′2, . . . , and S′(2n), which end parts are on a side of the data signal line driving circuit 102b. A preliminary wire 106b is provided so as to (i) extend to the region other than the display region R1 and (ii) intersect the other end parts of the respective data signal lines S′1, S′2, . . . , and S′(2n).
The repair amplifier circuit 104b has (i) an input terminal to which the preliminary wire 105b is electrically connected and (ii) an output terminal to which the preliminary wire 106b is electrically connected.
The control substrate 108 includes an electric power generating circuit and a timing controller (both of which are not illustrated).
According to the configuration, in a case where an electrically disconnected part (see an “X” in FIG. 25) is found in the data signal line S1 during a process of inspecting the liquid crystal display device 109, it is possible to short-circuit (electrically connect) the data signal line S1 with the preliminary wire 105a and the preliminary wire 106a. 
As such, the data signal line driving circuit 102a can (i) supply, as usual, a data signal toward the electrically disconnected part via the end part of the data signal line S1, which end part is on the side of the data signal line driving circuit 102a and (ii) also supply the data signal toward the electrically disconnected part via the preliminary wire 105a, the repair circuit 104a, the preliminary wire 106a, and the other end part of the data signal line S1.
It is therefore possible to supply the data signal to the whole data signal line S1 which has the electrically disconnected part.
Further, in a case where an electrically disconnected part (see an “X” in FIG. 25) is found in the data signal line S′3, it is possible to supply, in the same manner as the above, a data signal to the whole data signal line S′3 which has the electrically disconnected part.
The liquid crystal display device 109 thus includes the repair amplifier circuits 104a and 104b, and the preliminary wires 105a, 105b, 106a and 106b. Therefore, even in a case where a defect, such as electrical disconnection of the data signal lines S1, S2, . . . , and S′(2n), occurs, it is possible to drive the liquid crystal display device 109 by repairing the defect.